Delayed and brightened sweep circuit



March. 1958 R. F. CASEY DELAYED AND BRIGHTENED SWEEP CIRCUIT Filed June18, 1954 m P WT AHU \GIO 6. INVENTOR.

ROBERT ECASEY ATTORNEYS United States Patent 2,825,848- DELAYED ANDBRIGHTENED SWEEP CIRCUIT Application 'Juneis, :1954, Serial No. 431,8087 Claims. (Cl. 315- 22) This invention relates to improvements insweep-circuits as usedin cathode raytube instruments such as-are generaly'adapted to show an entire wave-form.

I An object-of this invention is to provide improvements in suchcircuits for facilitating the display of a desired and particularportion of a wave form.

Another object of the invention is toprovide improvemerits in suchcircuitsiwhich permit of the study oiany 'portion of a wave Tform.

Another object of this invention is to provide cathode ray tube circuitswith means for expanding the selected portion of a particular wave formto Yfull scopeflfor more detailed viewing.

Still another dbj'ectof'the invention is to provide a cathode raytuh'ecircuit capable of intensifying the selecte'd por'tionof the traceof afp'oftion of a wave form.

Stillfandtht object is tolpr'ovide a circuitby means of whichlit"isjpossible' to establish the selected portion of awaveform atso'mede'finite proportion of the originalyvave form.

V hose and 0 her" objects will he apparent'from the" following detaileddisclosure ofthe'ernbo diment of the i'nvention selected forillustrative 'purp'osesherein.

the accompanying drawings,

I'Figure 1 is a diagrammatic ands'chematieviewhf the circuit of thisinventien-,-afid Figure '2is a chart'sho at various points in saidcircuit.

For the purpose ofclarifying the disclosure the followi'ng -deiinitionsare proposed; upvoltin means raising ap'o'tential biitnot'necessarily'toapositive'value; downvetting means "lowering "apotential but-notnecessarily f6 anegative value.

' Bfdadl-y speaking this invention involves a delay cir caterer cathodei ray instrumentation arranged "to control two' le eneiseuarge tubes,one dfwhieh'providesregulatioh fo r -the b ghtness-volt'age of 'thecathode ray tribe and the othe'r' -a eep voltage 'entirely' independentof'the i tiiig' 1ve1tag'e soure.

Fer purposes of explanation it 'v'vill be assumed that a simp'le-sawt'ooth" voltage forniati'on will be used both forthe :swee controland the brightness control "-for a cathode ray 'tube, although thoseskilled'in'the' 'art will readily fappreciate that more complicated wave'forms for these'lpui'pos'es may'b'e employed.

The circuit of this invention is essentially based upon electrondischargedevices' with-associating circuits in accordance with'thisinvention to provide 'for'the objects hereimset-iorth. At 10 isdiagrammatically illustrated a -source of-sawtoothsweep-voltageregardl'ess of its mode of; generation, together with asource ofbrightnessvoltage output, which is characterized as being anAsweep source. This source .has the .usual output terminals 16 and 7-2which are the A sweep output and A brightness output, as indicated'inthe drawing. Terminal 16:.feeds agrounded potentiometer 70, the movablecontact .ofwhich is connectedfto'the'control grid of a triode 20 whosecathode-2'1is'groundem'as'shown. Theanode 23 is prong the related waveforms 2,825,848 zPatented Mar. 4, 1958 ice vided with proper operatingpotential from the positive side of a suitable source B (notshown)through a resistor in the usual manner, and this anode is also connectedthrough a pair of series connected resistors 12 and 14. to the negativeside of the B source.

-A pair of triodes 30 and 40, which .for the sake of description areherein sometimes referred to as the switchtube 30 and thebrightness-tube40, have their grids :32 and 42 connected'in series through anintermediate rests ltor76 to thejunctionpoint of the resistors 12 and 14and tothe cathode 61-of :awdiode fill. The cathodes 3:1 and 41 areconnected .to ground, as shown. Anode -43 .is connected to an output.terminal 71, which isdesignated R Brightness output which in .turn ds..connected=.to the Abr'ightness output terminal 72 and the 33+.-.terniinal by a voltage .dividerstl.

Anode '33 of the switch-.tubell' is connected .to :the coritrdlelectrode 52 of a triode 5.0 which .is thetswe'eptube of the R sweepsource, which is shown assa-wunit enclosed within the dotted :rectangle73. This connection includes agrdunded sweep-capacitor 74. Thercatlrode551 of the sweep'tube .50 is connected :throngh the resistor '77 to theanode 63 ofihe rectifier diode60 whose anode is also connected to B-through the resistor 78. Anode 53 is connected to B+ and an' adjustablevoltagetdivider 90 is shunted across the anode .53randz'cathode 51 withthe usual resistor rinthe anode lead. A voltage-regulator VR of anysuitable form is shunted across this voltage divider in the usualmannerand the-movable contact-thereof is connected throughasuitable resistorto theicontrol gridSZ of the .sweep-tubeiSll. .At 75:is-.the sweepoutput lead.

In .substance, there is provided as arliunct =torthe sweep supply (Asweep source) .fona cathode ray tOSGil-ifii graph designed .to .show an-entire wave ..form, :another sweep source .(R vsweep source) withinterconnecting circuitry, whereby a :particular portion of a-wavefdormcan be selected amplifiednnd intensified, thereby-enhancing the utilityof oscillograph instrumentation.-

The operation :of this circuit will snow tbetdescribed. Tube 20comprises an inverter .stage on whose control electrode 22 is applied .apotent-ialifromtthevterm-inalvlifi oi'the source 10'throughapotentiometer 7.0. .Byr-adjustirig the potentiometer .any desireddelaytin zthetoper ating effect of :theA.sweep-voltagewanibe obtained.{The inverted output .offthelinverter tube .20 which istnow -,a negativegoing voltage is applied :simultaneously-tto :the control electrodes .32.and4-2' of the'switch-tub'e athand the brightness-tube AllofitheRsweepsource; Since ethe rectifier 60 atthis :point is non-conducting; the-potentials applied to the .electrodesr32 .and- 42 iare iopen circuitpotentials.

Brightness-tube 40 is thus .cutrotl .-by. the tnegativewoltiage-.appliedto itscontrol electrode-42;,---so thatiitseanode 43 -isimmediately vupvolted .to1practicall y thepotent-ieil oi/the 13+terminal .cf t-he source. This increasedupw tential appears :at thebrightnessioutput!terminal.'hl and at a somewhat lower value at.thetoutputterminal'fli, Where'the :A' brightness voltagedue' only tothe ia sweep circuit lti usually appears. Ihe A' swee 1 provided with-"a'brightness-tube similar tome-brightness tube 40 so-thatthere isproduced-the brightnesswoltage from'that' 'c'ircuit. It is obviousthatthese"brightnesstubes are so called because-they determine thebrightness voltage at theterrnin'als'il and72.

Likewise, anode 33 is upvolte'dby the negative voltage applied to"its"control electrode 32. -As aresult swee capacitor 74 charges up andarm: same time sweep-tube 5% becomes conductivebecause its controlelectrodes; is likewise upvo-lted. Theresultis that the second svv'eepcircuitythat is "theTRTsw'e'ep circuitgis activated anti "211Rsweep-voltage appears at its output terminal 75. Here wave form underinvestigation. Resistors 77 and 78, deagain we see the reason forcalling tube 30 a switch-tube pending upon their adjustment, control theduration of since it switches on and off the R sweep circuit the studysection L and may restrict it to a desired defi'nte During theseoperations the control electrodes 32 and percentage of the A sweep The Rsweep t1me-constant, 42 remain at the same open circuit potential asdetermined 5 as determined by the sweep-capacitor 74 and voltage by thenon-conductive rectifier 60 and the potential at divider 90 regulatesthe magnitude A of the deflection anode 23 of the inverter tube 20. Whensweep-tube 5O voltage becomes more conductive its cathode 51 is upvoltedby The benefits to be derived from this invention are nucathode followeraction in following the rising potential merous. For instance, the useof the A sweep shows the applied to control electrode 52. The upvoltingof cathode entire wave form on the cathode ray tube. Using the 1 causesa corresponding upvoltmg of anode 63 of the combination of the A sweepand combination A and R rectifier so that it eventually becomesconductive that is hrlghthess p rmi n Observer to Select a Study Seehohwhen the potential of anode 63 exceeds the potential of Whleh 1eIndicated y hrlghter trace Whose length may cathode 61. s soon as therectifier becomes conductive be Selected at will. Switching to the Rsweep and the control electrodes 32 and 42 are upvolted restoring full Rbrightness expands the study section to utilize the entire conductivityto the brightness-tube 40 and partial con- Viewing area of the Cathoderay tube screen ducttvlty to the switch-tube 30, as determined byresistors It W111 be pp to those Skilled In the that Whlle 76, 12, and14. one embodiment of invention has been described When Rbrightness-tube 40 becomes conductive it others will readily occur. Forthis reason it is preferable anode 43 is downvolted, thus terminatingthe increase of not to be limited to the examples herein Used forthusvoltage at the terminal 71. The R sweep circuit 73 howtrativepurposes, but y as required y th appended ever holds since anydownvolting of sweep-capacitor 74 claimsand hence control electrode 52would also downvolt cath- W is Claimed ode 51, which action istransmitted through diode 60 to 1. In combination with a sweep circuithaving a sawanode 33 to thereby charge sweep-capacitor 74 to itscomprising: a second sweep circuit having a second sawinitial value.tooth output and a second brightness output, a network However, when theinitiating A sweep retraces it causes interconnecting said brightnessoutputs, whereby the trace retrace of the R sweep in the followingmanner. On on a cathode ray tube may be intensified; means enerrctracecontrol electrode 22 is quickly downvolted, regized by said first sweepcircuit for activating said second olf and eventually the circuitthrough the rectifier is predetermined interval which corresponds withthe acbro en, which occurs when the potential of anode 63 falls tivationof said second sweep circuit. elOW the Potential of cathode 61. Thecombination of claim 1 wherein said activat- It will be recalled thatswitch-tube 30 had been eming means comprises an inverter tube connectedacross ploying the connection through the diode 60 to balance the outputof said first sweep circuit. he disch rge of sw py p 74 against thecharging 3. A circuit for selecting the position and length of eetloll PP elfelht NOW, however; Since h a portion of an oscillograph trace forincreased illuminadiode elreult h been Interrupted sweep-capacitor 74can tion, the circuit being of the type including a first sweep p ydischarge through the Switch-tube 30 its upvolted circuit and a secondsweep circuit, each sweep circuit control electrode 32 permittingheavier conduction. The having a awtooth voltage output and arectangular voltdischarge of the pp 74, by e h Off the age brightnessoutput; the circuit comprising, in combinasweep'tuhe 50, also cuts offthe R sweep cll'culte thus the tion, means for combining the brightnessvoltage outputs sweep tehhihated by the A sweep of the first and secondsweep circuits, means for main- Ih.rev1ew It Wlh noted that h ahInterval Freda taining the combined brightness output at a selectedlevel termmed by the setting of potentiometer 70 after the comprising anormally conductive brightness electron A w i the A sweep and Abrightness volt tube associated with said second sweep circuit means toages at t F termini} s 16 and 72 i unchanged At the render saidbrightness electron tube non-conductive to determined by the resistors77 and 78, which may be adjustable as shown in the drawings, increasedbrightness voltage at the terminal 71 is terminated. At the end of the Asweep, the R sweep is also caused to retrace.

which could refer to the use of the invention herein disthe combinedbrightness voltages of curves 2 and 3. The lheahs operable by said f hfor initiating opera sweep appears in curve 5 Wlth regard to time oralong tion of the second sweep circuit, and means operable the w ve formf curve 1, rve 6 shows h enlarged when the sawtooth voltage output ofthe second sweep study section which wa elect d d b d by applycircuitreaches a selected value for restoring conductivity plates of thecathode ray tube. It will be understood that 7 return the Combinedbrightness Voltage output to the a switch is provided to permltconnection of the honselected level thus determining the length of thetrace zontal deflection means of the cathode ray tube to the potionhaving increased illumination. A or R sweep output. 4. A circuit forselecting the position and length ofa Adjustment of control determinesthe delay D so portion of a oscillograph trace to be more intensely 11-that the study section may start at any portion of the luminated and tobe enlarged, the circuit being of the type including a first sweet;circuit and a second sweep circuit; each s'weep 'circuivhavin'g a=sawt'odth vanes burput-and a brightness vdltage output; the dir'cuit'cem prising, in combination, means for combining the brightness voltageoutputs'ofthefirst and second "sweep circuits,

means for maintainingthe combined brightness output at a selected levelcomprising a no" allyconductive brighttress electrontube specificallyassociated with saidsec'oiid sweep "circuit, means to render saidbrightness electron tube nob-conductive to increase the combinedbrightness output voltage above the selected level, means to delayflie'said increase of combined brightness outputvoltage with respect tothe sawtooth sweep ofthe first sweep cirui'ttodetermine the position ofthe "initial point of the iritensifi'ed trace portion, said delaym'eanscomprising-a normally non-conducive inverter electron tube, meansfdrrenderin'g said inverter tube conductive when the sawtooth outputvoltage of the first sweep circuit reaches a predetermined level, aswitch tube in the second sweep circuit, means for rendering said switchtube operative simultaneously with said brightness tube of the secondsweep circuit, means operable by said switch tube for initiatingoperation of the second sweep circuit, means operable when the sawtoothvoltage output of the second sweep circuit reaches a selected value forrestoring conductivity to said brightness tube of the second sweepcircuit to return the combined brightness voltage output to the selectedlevel, thus determining the length of the increased illumination traceportion, means for adjusting the time constant of the second sweepcircuit to determine the length of the intensified portion of the trace,and means for maintaining the sawtooth voltage output of the secondsweep circuit at said predetermined level to thereby prevent retrace.

5. A circuit for selecting the position and length of a portion of anoscillograph trace to be more intensely illuminated and to be enlarged,the circuit being of the type including a first sweep circuit and asecond sweep circuit, each sweep circuit having a sawtooth voltageoutput and a brightness voltage output; the circuit comprising, incombination, means for combining the brightness voltage outputs of thefirst and second sweep circuits, means for maintaining the combinedbrightness output at a selected level comprising a normally conductivebrightness electron tube specifically associated with said second sweepcircuit, means to render said brightness electron tube non-conductive toincrease the combined brightness output voltage above the selectedlevel, means to delay the said increase of combined brightness outputvoltage with respect to the sawtooth sweep of the first sweep circuit todetermine the position of the initial point of the intensified traceportion, said delay means comprising a normally non-conductive inverterelectron tube, means for rendering said inverter tube conductive whenthe sawtooth output voltage of the first sweep circuit reaches apredetermined level, a switch tube in the second sweep circuit, meansfor rendering said switch tube operative simultaneously with saidbrightness tube of the second sweep circuit, means operable by saidswitch tube for initiating operation of said second sweep circuit, meansoperable when the sawtooth voltage output of the second sweep circuitreaches a selected value for restoring conductivity to said brightnesstube of the second sweep circuit to return the combined brightnessvoltage output to the selected level, thus determining the length of theincreased illumination trace portion, means for adjusting the t'meconstant of the second sweep circuit to determine the length of theintensified portion of the trace, means for maintaining the sawtoothvoltage output of the second sweep circuit at said predetermined levelto thereby prevent retrace, and means for terminating said delay ofretrace of the second sweep circuit upon retrace of the first sweepcircuit.

6. A circuit for selecting the position and length of a portion of anoscillograph trace and for enlarging said selected portion andincreasing the intensity of illumination thereof, the circuit being or btype includingafiis't sweep circuit and as'e'cbndsweep circuit, eachhaving a sawtooth voltage swee'pbu'tput anda rectangular voltagebrightness output; "comprising, in combination, a resistance networkiriterco'rrne'c :u'g saitl brightness voltage ontputs, means including abrightness electron tube associated with said second sweep cir'c" it formaintaining 'th brightness "outputaf'a'sl'ect'ed level, said tube havingacathode, 'anode and-control 'grid-, a"n inverter electron tube, meansapplying thesawtooth output voltage of the first sweep circuit to "saidinverter tube, a switch tube having an anodeycathode and control grid,the anodecathbde circuit of said switch tube being connected in parallelwith a sweep capacitor of the second sweep circuit,"-a "connection froms"'dinverter tube 'output to the grid of said switchtub'e, 'a "resistorco" nectingsaidswitch tube grid to said brightness tube grid, saidinverter tube serving to render said switch tube and said brightnesstube simultaneously non-conductive, said switch tube initiating chargingof the sweep capacitor of the second sweep circuit, said brightness tubeincreasing the combined brightness voltage output, means to terminatethe operation of said second sweep circuit and associated brightnesstube when the output of said second sweep circuit reaches apredetermined level, said means comprising a voltage divider connectedto the sweep output of the second sweep circuit, a diode having an anodeconnected to a point on said voltage divider, and a cathode connected tothe control grid of said brightness tube, said diode being renderedconductive when the sweep output voltage reaches a predetermined levelto thereby return said brightness tube output to its predeterminedlevel, said diode when conductive maintaining said switch tube at acontrolled conductivity to thereby delay the retrace of the second sweepcircuit whereby a single cathode ray tube oscillograph will produce anintensified illumination of a selected trace portion when the deflectionplates thereof are connected to the sweep output terminals of the firstsweep circuit and will enlarge and intensity said selected trace portionwhen the deflection plates are connected to the sweep output terminalsof the second sweep circuit.

7. A circuit for selecting the position and length of a portion of anoscillograph trace and for enlarging said selected portion andincreasing the intensity of illumination thereof, the circuit being of atype including a first sweep circuit and a second sweep circuit, eachhaving a sawtooth voltage sweep output and a rectangular voltagebrightness output; comprising, in combination, a resistance networkinterconnecting said brightness voltage outputs, means including abrightness electron tube in said second sweep circuit for maintainingthe brightness output at a selected level, said tube having a cathode,anode and control grid, an inverter electron tube, means for applyingthe sawtooth output voltage of the first sweep circuit to said invertertube, a switch tube having an anode, cathode and control grid, theanode-cathode circuit of said switch tube being connected in parallelwith a sweep capacitor of the second sweep circuit, a connection fromsaid inverter tube output to the grid of said switch tube, a resistorconnecting said switch tube grid to said brightness tube grid, saidinverter tube serving to render said switch tube and said brightnesstubes simultaneously non-conductive, said switch tube initiatingcharging of the sweep capacitor of the second sweep circuit, saidbrightness tube increasing the combined brightness voltage output, meansto terminate the operation of said second sweep circuit and associatedbrightness tube when the output of said second sweep circuit reaches apredetermined level, said means comprising a voltage divider connectedto the sweep output of the second sweep circiut, a diode having an anodeconnected to a point on said voltage divider and a cathode said invertertube then rendering said switch tube conductive and causing the secondsweep circuit to retrace. References Cited in the file of this patentNITED STATES PATENTS retrace of the second sweep circuit whereby asingle 2,305,930 Martinelli Dec. 22,1942 cathode ray tube oscillographwill produce an intensified 2,355,363 'Christaldi Aug. 8, 1944illumination of a selected trace portion when the defiee- 2,368,449 CookJan. 30, 1945 tion plates thereof are connected to the sweep output 102,399,955 Theisen May 7, 1946 terminals of the first sweep circuit andwill enlarge and 2,440,263 Grieg Apr. 27, 1948 intensify the selectedtrace portion when the deflection 2,453,711 Isbister et a1 Nov. 16, 1948plates are connected to the sweep output terminals of 2,492,700 JeanneDec. 27, 1949 the second sweep circuit, said inverter electron tube2,501,110 Walker Mar. 21, 1950 being restored to conductivity by thedecreased sweep 15 2,620,455 Fodder 2 voltage output of the first sweepcircuit upon retrace, 2,648,027 Geohegan Aug. 4, 1953

